וַיַּקְהֵל מֹשֶׁה אֶת כָּל עֲדַת בְּנֵי יִשְׂרָאֵל וַיֹּאמֶר אֲלֵהֶם אֵלֶּה הַדְּבָרִים אֲשֶׁר צִוָּה ה' לַעֲשֹׂת אֹתָם.
"And Moshe assembled the entire assembly of the Children of Israel and said to them: “These are the things that Hashem commanded, to do them” (Shemos 35:1).
Why does the Torah have to tell us that Moshe “assembled the entire assembly of the Children of Israel”? Weren't the Jews also assembled by all of the other mitzvot?
On this verse, Rashi explains as follows: למחרת יום הכפורים כשירד מן ההר - “He assembled them on the day after Yom Kippur when he came down from the mountain.” Why does Rashi tell us when the assembly took place? What difference does it make when the essembly took place?
It can be explained as follows: The Torah says that Hashem spoke to the Children of Israel at Har Sinai with קוֹל גָּדוֹל וְלֹא יָסָף - “a great voice, which did not cease” (Devarim 5:19). The Targum explains that this voice never ceased, even after the giving of the Torah on Har Sinai. The voice of Hashem can still be heard, but one has to purify himself greatly in order to merit to hear that voice.
Therefore, as long as the Jews didn’t sin at the Golden Calf, they still heard the sound of Hashem, but after they sinned they could no longer hear the voice and they were afraid that they will never again be able to hear the voice of Hashem.
However, after Yom Kippur when Hashem said סָלַחְתִּי כִּדְבָרֶךָ - "I have forgiven them in accordance with your word” (Bamidbar 14:20), the Jews were pure again and they could hear the voice of Hashem as before.
With the above explanation, we can understand the verse as follows: The word “Vayakhel” has the same letters as the words קול הוי”ה - “The voice of Hashem.”
Moshe Rabbeinu assembles the Children of Israel and he told them that as long as we purify ourselves, we can once again merit to hear the sound of Hashem coming from Har Sinai.
Therefore Rashi adds that the Jewish people were assembled after Yom Kippur, because after Hashem forgave them, they were once again merited to hear the voice of Hashem.
Today (24th of Adar ) is the yahrtzeit of Rebbe Itzik’l Stitchiner, zy”a. He had a custom of wearing his tallis when making kiddush on Shabbos morning, and also while distributing the mezonos and kugel.
Once when he wasn’t feeling well, the doctors told him to avoid eating kugel. On the following Shabbos, he saw that his Chassidim are not bringing out the kugel, so he told them “I know that I can't eat the kugel, but at least let me distribute it!”
He told them that his grandfather, the Holy Ropshitz’er, once went on a stroll with the Holy Rebbe R’ Mendel of Riminov, and for three hours R’ Mendel explained to him the lofty meaning of eating kugel on Shabbos. So R’ Itzik’l told his Chassidim, “I can’t explain the meaning of kugel for three hours, but at least let me distribute kugel for three hours.”
(קידושא רבא - תשס"ה)